1. Field of the Invention
The present invention relates to a stereoscopic image recognition apparatus capable of improving luminance and enabling an image having a slight color variation to be recognized without crosstalk when a liquid crystal display which projects images displayed in a stereoscopic manner by a time division scheme is viewed in front and obliquely.
2. Background Art
As a stereoscopic image recognition apparatus which has a liquid crystal display mainly including a liquid crystal cell, and a pair of polarizing plates interposing the liquid crystal cell therebetween, and a time division image display shutter which includes a polarizing plate in a form of glasses or the like and a liquid crystal cell, there is known a stereoscopic image recognition apparatus disclosed in JP-A-53-51917 and JP-A-2002-82307 and the corresponding US 2002/0044350. In addition, the time division image display shutter is called liquid crystal (hereinafter, abbreviated to LC in some cases) shutter glasses when it is in a form of glasses. Such a stereoscopic image recognition apparatus is viewed in a state where, typically, the liquid crystal display stands vertically with respect to the ground, and the time division image display shutter is disposed in parallel to the ground (the eye of a viewer is parallel to the ground).
As a configuration of the stereoscopic image recognition apparatus, there is a configuration in which a λ/4 plate is disposed on a viewing side of a display side polarizing plate of the liquid crystal display, and a liquid crystal sealing body such as a liquid crystal cell and a λ/4 plate are disposed outside (opposite side to the viewer side) a polarizing plate disposed at the viewer side of the time division image display shutter. (Hereinafter, a configuration of the time division image display shutter having two polarizing plates is referred to as two-polarizing plate type time division image display shutter, and a configuration having one polarizing plate is referred to as a one-polarizing plate time division image display shutter.)
However, in the stereoscopic image recognition apparatus described above, at least one polarizing plate is used in the time division image display shutter, and thus it is known that luminance of a display screen is theoretically reduced. In order to obtain 3D display having high display definition, it is important to suppress reduction in luminance of a display screen as much as possible.
Since a stereoscopic image recognition apparatus in the related art does not use a λ/4 plate, there is a problem in that if the face is tilted in a case where the liquid crystal display is viewed in front, a display screen is darkened, but, in a stereoscopic image recognition apparatus using two λ/4 plates, it is possible to prevent the display screen from being darkened even if the face is tilted when the liquid crystal display is viewed in front.
In addition, in a case of the one-polarizing plate time division image display shutter, a flickering phenomenon unique to the stereoscopic image recognition apparatus can be suppressed; however, there is a problem in that a distinction between a right eye image and a left eye image, which is a mechanism for recognizing a stereoscopic image, is not completely recognized, and a so-called crosstalk phenomenon occurs in which the images are seen to overlap each other by a viewer when the liquid crystal display is viewed obliquely.
In relation to the latter crosstalk problem, as a solving means, a technique is disclosed in JP-A-2004-226945 and the corresponding US 2005/0151906 in which a member used as a λ/4 plate is formed on a transparent support by aligning discotic liquid crystal.
If the negative (−) plate A disclosed in JP-A-2004-226945 is applied to the stereoscopic image recognition apparatus disclosed in JP-A-2002-82307, it is proved that the crosstalk phenomenon is greatly reduced.